The present invention relates to an inductance element for use in a mobile communication equipment, power supplies and other electronic apparatus.
An example of conventional inductance elements is described in Japanese Utility Model Laid-Open No. S61-144616: a chip coil shown in FIG. 12 perspective view. The chip coil is composed of a body 1 provided with flanges 2, 3 at both ends of a winding area 4, and a coil 6 wound around the body 1. The flanges 2, 3 are provided with a cut 5 for holding the end portion of the coil 6, respectively. Since a chip coil of the above configuration is free from the polarity, the efficiency of mounting the chip coil on a circuit board is high; therefore, the productivity in circuit board manufacture is increased. Furthermore, since the coil 6 does not protrude above the flange surface, or the surface of connection, it has a superior surface mounting stability.
Other examples of conventional inductance elements, composed of a body and a coil wound around the body, are disclosed also in, for example, Japanese Patent Laid-Open Nos. H8-124748, H8-124749, H8-213248 and H9-306744, and Japanese Utility Model Laid-Open No. H3-1510. Japanese Patent Laid-Open No. H10-172832 discloses an inductance element that is provided with a tapered portion between the winding region to be wound by a coil and the flanges functioning as terminals disposed at both ends.
However, in the above-described configuration, where the wire diameter of a coil is compelled to go less and less along with the down-sizing of an inductance element, deterioration in the Q factor is significant.
Further problem with the above-described conventional inductance elements is that it is not easy to judge by an image recognition process whether an inductance element is acceptable or is to be rejected, since the terminals at both ends of body is normally colored silver, and color of the body is normally white. Recognition errors often arise at the judgement, ill-affecting the productivity.
The present invention addresses the above problems, and aims to offer an inductance element that is a coil-type and yet provides an improved Q factor and other characteristics even with a down-sized configuration.
Another objective of the present invention is to offer an inductance element with which a judgement on the terminal electrodes is performed surely with ease; hence the productivity may be improved with the inductance elements.
An inductance element of the present invention comprises a column-shaped body, a coil wound around the body, terminal electrodes provided at both ends of the body for connection with the coil and a protection material for covering the coil, which protection material having a relative dielectric constant not higher than 6.0. The Q factor can be improved by the use of a protection material whose relative dielectric constant is not higher than 6.0 in the above-described configuration.
It is preferred in an inductance element of the present invention that the outermost layer of each terminal electrode has a color that is different from the colors of the body and the protection material. The difference in the colors remarkably contributes to reduce the image recognition errors and to improve the productivity. The earlier-described erroneous judgement occurred with the conventional inductance elements seems to have been caused by a recognition error that the terminal electrode has been recognized to be larger than specified dimensions because of an apparent resemblance among the colors of the body and the terminal electrode. The reduced recognition error with the inductance elements of the present invention seems to be a result of the differentiated coloring.